Low dose rate effects on linear bipolar IC's: Experiments on the time dependence

The time dependence of radiation-induced damage to a bipolar microcircuit has been studied at three dose rates. It is found that both time dependent effects and "true" dose rate effects must be considered to fully characterize the radiation response of these devices. An empirical model is constructed in an attempt to describe the response of these devices both during and after the irradiation. It is found that this model can successfully characterize the time dependent effects observed in these devices, as well as demonstrate some fundamental differences in the radiation response at different dose rates. This model in its present form, however, is shown to be insufficient to explain the results of several experiments where the devices are subjected to sequences of alternating irradiations and anneals. The consequences of these results and possible mechanisms are presented.